[Elfsea] Microwaving Metals- From the VirtualJunkyard

[Betsy Marshall]

And Pyro says "Hmmm..."

-----Original Message-----
From: sca-cooks-bounces at ansteorra.org
[mailto:sca-cooks-bounces at ansteorra.org] On Behalf Of Phlip
Sent: Friday, January 02, 2004 10:08 PM
To: SCA-Cooks; EKMetalsmiths at yahoogroups.com
Subject: [Sca-cooks] Fw: [TheForge] Microwaving Metals From the
VirtualJunkyard


Just got this off TheForge- I think you Cooks might understand my
amusement.
Adam, don't try this at home, your MinL will never forgive us ;-)

Saint Phlip,
CoDoLDS

"When in doubt, heat it up and hit it with a hammer."
 Blacksmith's credo.

 If it walks like a duck, and quacks like a duck, it is probably not a
cat.

Never a horse that cain't be rode,
And never a rider who cain't be throwed....

----- Original Message -----
From: "Rob Fertner" <rfertner at cox.net>
To: <theforge at mailman.qth.net>
Sent: Friday, January 02, 2004 10:31 PM
Subject: [TheForge] Microwaving Metals From the Virtual Junkyard


> Over on keenjunk.com this was posted. It sounded so interesting I just
had
> to share with the rest of you.
>
> Copied from the Virtual Junkyard:
> Friend of mine sent me this thought y'all might enjoy it
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+++
> Subject: [hobbicast] Microwave Melting Update
>
>
> Some of you may know that I make a living by developing new products
> and
> processes for the metal casting and steel making industries. About 6
> months ago,
> we started looking seriously at using microwave energy for melting
> metals.
> About $40,000 later, we have done an immense amount of lab work. We
> have
> successfully melted Aluminum, Bronze, Iron, Steel and even Glass in a
> simple 1000 watt
> microwave oven. The key points in doing this are as follows.
>
> 1. You need do have either a special crucible that absorbs microwaves,
> or,
> you will need to have microwave absorbing materials nearby to a
> microwave
> transparent crucible.
>
> So far, we have made all of our own crucibles. I can't tell you what
we
> are
> using, because we fully intend to offer these crucibles for sale to
the
> public,
> sometime this year. What I can tell you is that Silica (fused silica)
> is
> microwave transparent. Alumina becomes a microwave absorber at
elevated
> temperatures. Once you get it hot, it will get very hot, very quickly
> in microwave
> energy. We have developed a mixture of refractories that can be shaped
> into a
> crucible that will reach over 2,000°F. in less than 5 minutes of
> microwave heating.
>
> 2. You will need to use some fairly fancy refractory insulation to
keep
> from
> burning up the inside of the microwave. We use a very low density
solid
> or
> fibrous material that is about 70% Alumina and 30% Silica. You can
> either build a
> box and then put the crucible inside of it, or, you can line the whole
> inside
> of the microwave. Just remember that the radiant heat from a glowing
> crucible
> needs to be contained, or you will quickly burn the inside of the
oven.
> Remove any plastic covers inside the microwave, or they will melt.
>
> 3. You really need to keep close tabs on the temperature of the metal
> in
> order to avoid some serious over heating disasters. Last month, we
over
> heated
> some Iron, which then melted through an Alumina crucible (that takes
> 3700°F), and
> then we vaporized the Iron (that takes about 5000°F). Things can get
> really
> hot really fast. Be prepared to shut down the power if you get into
> runaway
> heating. Have some really well insulated gloves or tongs to handle the
> crucible.
>
> 4. Now, here's the neat part. We know that metals behave as microwave
> reflectors. They won't heat up in a microwave. BUT, we have learned
> that all metals
> will become microwave absorbers at elevated temperatures. We suspect
> that the
> temperature at which this occurs is about half of the melting point of
> the
> metal. We will know what the exact temperatures are later in January.
>
> Once you reach this magical temperature, the metals will absorb the
> microwaves and you can melt lickety split! Virtually all of the energy
> that you put
> into the oven is going directly into the metal and causing molecular
> vibration
> (heating).
>
> DON'T DO ANY OF THIS KIND OF STUFF IN YOUR WIFE'S MICROWAVE!
>
> I have toasted 3 microwaves in the past 3 months, mainly because they
> got too
> hot from runaway heating. I melted through the bottom of one and the
> Iron ran
> out onto the table, along with a fair amount of microwave energy,
which
> can
> be quite dangerous. If you are serious about doing this, you need to
> constantly
> measure for microwave leakage from the unit.
>
> I expect to make a public announcement about the availability of these
> special crucibles and the refractory insulation for holding them,
> sometime in the
> next 3 months. This is no BS. We are quite serious about designing a
> microwave
> that will have the capability of melting at least one ton per hour, by
> the end
> of 2004. The eventual goal is to design and build a system that can
> melt
> several hundred tons a day.
>
> I will keep all of my Hobbicast friends posted on our progress.
>
> Tom Cobett
> Cleveland, OH
>
> "In Pyro Veritas"


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